am I pregnant or is it just side effects


So this Sunday that just passed I started taking my birth control pills due to me just getting off my period I am on day 4 of my birth control pills and I am always nauseous, cramping, headache, not being able to eat anything but fruit and vomiting constantly I am worried that I might be pregnant I am too young I don't want children at this point in my life..... are these common side effects to being on birth control or should I be worried